1. Field of the Invention
The present invention relates to a method for detecting a fine frequency deviation generated in a transmission line such as a general public telephone switching network.
2. Description of the Prior Art
Frequency deviations generated in transmission lines are little worth consideration when signals to be transmitted are voice signals. In data transmission using an adaptive equalizer, a signal having a frequency deviation serves as a factor of interfering with a transmission circuit adaptation function of the adaptive equalizer.
In the latter case, the degree of the frequency deviation generated should be accurately detected so as to compensate the frequency deviation. In some cases, the degree of the frequency deviation is utilized as a measure for evaluating the transmission quality of communication lines.